Train communication system with silent compartments

ABSTRACT

A method and system for wireless communication between a public transport vehicle and a remote server through at least one external mobile network are disclosed. At least one router is provided in the public transport vehicle for receiving and transmitting wireless data to and from a stationary communication server outside the public transport vehicle and to and from at least one client onboard the public transport vehicle. The router determines if a stream of wireless data packets received by said router corresponds to at least one of a VoIP stream and a VoWIFI stream, e.g. by accessing a blacklist with predefined ports and/or destination addresses. It is further determined if the client associated with the stream is within the access area of an access point which is set in a silent compartment mode.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a wireless communication system for public transport vehicles, such as trains, and a related method.

BACKGROUND

The demands on wireless communication capabilities in today's society are increasing rapidly. In particular, fast and easily accessible communication is desired through hand-held devices over large areas. It is particularly challenging to achieve such communication for mobile devices which are moving, e.g. when moving over large distances with poor network coverage or when affected by unknown sources of noise interrupting a signal for communication, such as clients moving on e.g. trains, airplanes, busses and other types of public transport vehicles. In particular, if a client, such as a mobile phone, moves over large areas the client has to connect to several base stations in order to maintain a sufficient connection for communication.

This increasing demand from passengers to be able to communicate through mobile phones and other handheld terminals when travelling on e.g. trains, also includes an increased demand to be able to get access to the Internet with laptops, PDAs etc. Further, with the new smartphones, and the way these are used, with e.g. continuously operating applications, many phones are active at all times, meaning that many handovers are required when the train moves. Even though this problem is common for all public transport vehicles, it is especially pronounced for vehicles moving at high speed, such as trains and airplanes, and trains are in addition facing problems with poor line-of-sight between the base stations and the train. This puts a strain on the wireless network infrastructure, leading to poor performance.

Moreover, train carriages are made of metal, and even the windows are normally covered with a metal film. Accordingly, train carriages are shielded compartments, and direct communication between terminal antennas within the carriages and externally located antennas is difficult to obtain. The mobile nature of a client with respect to the base stations may also introduce several potential sources of communication performance degradation. Such sources may derive from complex terrain, competition for available channels, or the source may be an unknown source of noise related to e.g. radio-frequency interference.

To this end, public transport vehicles, such as train carriages, are often provided with an external antenna connected to a repeater unit within the carriage, which in turn is connected to an internal antenna. Hence, the communication between the passengers' terminals and the operator antennas outside the vehicle occurs through the repeater unit. Similarly, it is known to provide a mobile access router for data communication, also connected both to an external antenna and an internal antenna, in each carriage, in order to provide Internet access on board the vehicle. Such mobile access router solutions are e.g. commercially available from the applicant of the present application, Icomera AB, of Gothenburg, Sweden, and are also disclosed in EP 1 175 757 by the same applicant. This method has greatly improved the reliability of high-bandwidth wireless communication for trains and other large vehicles.

However, a consequence of the above-described developments is that many problems relating to the management of data are emerging, in particular due to the sheer volume of it. Moreover, presently known solutions regarding the management of data are often inadequate in terms of user (i.e. passenger) satisfaction and are furthermore oftentimes based on out-dated requirements and passenger needs.

Further, a specific problem in known communication systems of the above-discussed type is that voice communication, such as telephone calls, are very sensitive to disturbances, such as increased latency.

To this end, many attempts are currently made to make wireless communication for passengers on-board trains and other public transportation vehicles more efficient.

However, many passengers also have a need or desire for quietness and silence. To this end, many train operators and the like offer the possibility of travelling in quiet compartments, which may also be referred to as silent coaches, quiet cars, quiet zones, etc. In such compartments or coaches, you are supposed to behave quietly, and it is normally not allowed to speak loudly, or even speak at all. However, despite such rules, it happens frequently that passengers talk in their telephones, thereby disturbing the other passengers desiring silence,

To this end, many operators have deliberately not installed cellular repeaters in the silent coaches/compartments, thereby making it more difficult to make telephone calls. However, nowadays, many calls are made over the WiFi network instead of over the cellular network, e.g. using VoIP (Voice over IP) and a VoWIFI (Voice over Wi-Fi). The absence of a cellular repeater in the coach is consequently no longer efficient for prohibiting telephone calls and for enforcing the regulations. Further, even though it would be possible to remove also the access points for the internal WiFi network in the silent coaches/compartments, such a measure is not at all desirable, since it would also hinder silent use of the WiFi, such as e-mail correspondence, reading of newsletters, web browsing, etc. In fact, many passengers choosing to travel in a silent coach/compartment does this for the purpose of being able to work more efficiently, and these possibilities would be severely restricted and deteriorated if there were no access to efficient data communication.

There is therefore a need for an improved method and system for communicating with clients on public transport vehicles, and in particular trains, and specifically which provides improved measures to enforce rules of silence and quietness.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a new and improved method for wireless communication and a wireless communication system for a public transport vehicle, in particular a train.

This object is achieved by means of a method and wireless communication system as defined in the appended claims. The term exemplary is in the following to be interpreted as; serving as an example, instance, or illustration.

According to a first aspect of the present invention there is provided a method for wireless communication between a public transport vehicle and a remote server through at least one external mobile network, comprising: providing at least one router in the public transport vehicle for receiving and transmitting wireless data to and from a stationary communication server outside said public transport vehicle through said at least one external mobile network via at least one antenna and being connected to at least one access point for receiving and transmitting wireless data to and from at least one client onboard the public transport vehicle;

determining if a stream of wireless data packets received by said router corresponds to at least one of a VoIP stream and a VoWIFI stream; determining if the client associated with said stream is within the access area of an access point which is set in a silent compartment mode; and

intercepting said stream if it has been determined that said stream of wireless data packets corresponds to at least one of a VoIP stream and a VoWIFI stream and that said client associated with said stream is within the access are of an access point set in a silent compartment mode.

Such a method can easily and efficiently ensure that telephone conversations in silent coaches or compartments on the vehicle is reduced or even made completely impossible. This improves the traveling experience for customers. It also ensures that all other data communication in the silent coaches/compartments is not at all affected, but instead as efficient as anywhere else in the vehicle.

The setting of access points to be in a silent compartment mode can also be made easily in software in the router, or by hardware, such as by a switch provided on the access point or the router. It may also be controlled wholly or partly from an external gateway or the like, communicating with the access points through the router. Hereby, reconfiguration of the system can be done very easily, so that access points can easily be configured and reconfigured to be in a normal mode or a silent compartment mode, depending on the circumstances.

As soon as the passenger leaves the silent compartment/coach, and enters into the access area of another access point which is not set in a silent compartment mode, the client device will roam to the access point in the new, non-silent coach/compartment, and VoIP and VoWIFI calls are again enabled. Thus, no other action is needed by the passenger than to change coach/compartment in order to enable or disable VoIP and VoWIFI calling.

The “router” (or sometimes “mobile router”) is a networking router, which is a machine that forwards data packets between computer networks, on at least one data link in each direction. The router may be a mobile access router, and preferably a mobile access and applications router. The router preferably comprises means for determining if a stream of wireless data packets received by the router correspond to VoWIFI call, the means being for example appropriate hardware and/or software, from here on referred to as a control unit. The determining step can be performed on a stream of wireless data packets received from a client onboard the public transport vehicle, or from a remote server outside the vehicle.

An internal LAN may be provided inside the public transport vehicle for providing wireless communication between the router and at least one client onboard. The at least one client onboard may accordingly be connected to said router via a LAN (local area network) provided by one or more wireless access points within the public transport vehicle. Preferably, at least one such wireless access point is provided in each carriage. All wireless access points may be connected to a single, central router, arranged in one of the carriages of a train. However, each carriage in the train may also be provided with a separate router connected to at least one wireless access point, where the wireless access point may be external to the router or an integrated function of the router.

Each stationary communication server may be any server or site accessible through the exterior mobile network, such as a DNS server, an ISP infrastructure gateway, an aggregation gateway, a content provider server of interest to vehicle passengers, or the like. For all common applications of this invention, the stationary servers will constitute the Internet, but partly or purely private network applications are also feasible.

VoWIFI may also be referred to as Wi-Fi calling, or GAN/UMA (Generic Access Network or Unlicensed Mobile Access). VoWIFI is in the present context to be understood as a solution whereby mobile service providers can deliver the same set of mobile voice and messaging services they currently offer over their macro cellular network, over any Wi-Fi network, globally. In short, it can be said that the cellular world has two separate core networks, called CS (circuit switched) that was used for voice and PS (packet switched) for data. As operators moved more and more voice communication over to the PS part two new terms evolved, Voice over HSPA/3G (VoHSPA) and Voice over LTE/4G (VoLTE), and subsequently it was realized that one can use WiFi to access the PS part of the network, hence, VoWIFI.

The VoWIFI is preferably used in accordance with the IEEE 802.11 standard, and may also be referred to as voice over WLAN (VoWLAN), but other wireless internet networks may also be used.

In more detail, VoWIFI enables the user to make standard phone calls over Wi-Fi. This is done by routing the call traffic through the Wi-Fi connection, instead of over the air to a cell tower. In VoWIFI the user dials the number, and places the call in a conventional way, just like in a circuit switched environment. However, the difference is that the call connects over Wi-Fi, and is transferred in data packets, and is subsequently injected back into the cellular network as if the call had been beamed over the air. Furthermore, an increasing number of smart phone providers are providing built-in support for Evolved Packet Core (EPC) integrated Wi-Fi calling support as part of their device fleet. This provides users with native Wi-Fi calling experience without any need to download a specific software application, but instead users can continue to use the built-in phone dialer and continue to be reached on their phone number. Unlike services like Skype, Viber, WhatsApp and other Over the Top (OTT) Voice over IP (VoIP) applications, which place calls using call forwarding or an internet-based interface, VoWIFI lets the user use the ordinary carrier phone number over the internet. VoWIFI is also distinct from VoIP technology in that VoIP transfers the voice over the internet to the switched telephone network, whereas VoWIFI connects the voice traffic to the mobile carriers network using the internet instead of cell towers. A wireless communication system capable of transferring voice communication via VoWIFI between at least one mobile terminal and an exterior mobile network is disclosed in the pending and still unpublished Swedish patent application No. 1451302-2, by the present applicant, said document incorporated herein by reference in its entirety.

“Data streams” are traffic in need of routing. A stream is in the context of the present application to be seen as any and all communication with a specific combination of ultimate source and ultimate destination IP addresses and network ports, or whatever the equivalent of this would be in a networking scheme where these identifiers are not used or not sufficiently distinguishing. A stream is “created” when any entity on one side of the system seeks to communicate with any entity on the other side, using any specific combination of ports. In a phone call made over VoWIFI, the entire call may be considered to constitute a single data stream, or may alternatively be considered to be formed of several consecutive data streams.

The router and the remote server are preferably connected through a plurality of exterior mobile networks, which are simultaneously useable. Also, the router is preferably arranged to communicate with the communication server on at least two different data links (communication routes) having different characteristics, where the characteristics can be measured by the router. These characteristics may include packet loss (intermittent failure for packets of data to arrive), latency (round-trip response time, hence responsiveness), jitter (the time variation of the latency), throughput (overall rate of data transmission, whether current or potential) and a variety of radiophysical metrics, such as signal strength. The data streams are then forwarded on one or several links to and from a dedicated external server, which may be referred to as an aggregation server or gateway. The different links thereby form a single virtual link between the router and the gateway.

The communication can be automatically optimized based on an evaluation based on the measured characteristics, and also optionally on other conditions, such as price. Thus, in addition to the evaluation, prioritizing and assignments may be made based on other static or dynamic parameters, such as signal strength and the like. Such further optimizations are per se known from EP 1 175 757 and EP 2 943 011 by the same applicant, said documents hereby incorporated by reference. An automatic selection is then made among the available data links to use the most efficient combination. Hence, a seamless distribution of the data among the different data links is obtained.

The router may use any available data links, such as two or more of e.g. GSM, Satellite, DVB-T, HSPA, EDGE, 1× RTT, EVDO, LTE, Wi-Fi (802.11) and WiMAX; and combine them into one virtual network connection. In particular, it is preferred to use data links provided through wireless wide-area network (WWAN) communication technologies.

The selection of links is preferably made once for each data stream. However, re-selection for data streams that have failed may also be made. Further, data streams may also be split among two or more data links, e.g. by transferring a first part of a data stream on one data link to begin with, and then continue the transfer of the rest of the data stream on another data link, based on a re-assignment decision. Re-selection and/or re-assignment may also be made based on other criteria than complete failure of the presently used data link, such as when the evaluated quality of the link presently used is significantly deteriorated, falls below a certain threshold, or the like.

The present invention is based on the realization that by providing a router onboard a vehicle that is capable of recognizing a stream of data that corresponds to at least one of a VoIP stream and a VoWIFI stream (a call request or on-going call), this may be used to ensure that silent compartments/coaches to a large extent remain silent and quite, which drastically improve passenger satisfaction and the overall traveling experience.

By means of the present invention, many time-saving and possibly cost-saving functions are provided for the passengers of a public transport vehicle. As discussed earlier, VoWIFI and VoIP services are starting to replace the more conventional calls (via a CS network), which has introduced new problems and inconveniences for operators trying to enforce rules regarding silence and quietness in certain areas of the vehicle.

Therefore, by having the router recognize that a client is attempting to make or receive a VoWIFI-call/VoIP-call, and when it is determined that the client is within the access area of an access point set in a silent compartment mode, such data streams can easily be intercepted, and blocked from being forwarded. This will drastically improve the overall passenger experience. However, if it is determined in the router that the stream of wireless data packets does not correspond to at least one of a VoIP stream and a VoWIFI stream, the router will forward the stream in the same way for all access points, regardless of whether they are in a normal mode or a silent compartment mode.

In the same way, interception can also be made for attempts to seamlessly handover on-going calls to VoLTE/VoHSPA/VoIP which have been established and initiated through the carrier's cellular data network (e.g. 3G, 4G, etc.). Thus, such calls will then be disconnected when the device switches over to the Wi-Fi network onboard the vehicle when an attempt for handover is made. The determining of a possible match between a stream of wireless data packets and at least one of a VoIP stream and a VoWIFI stream is in one exemplary embodiment based on packet size and pattern of a packet stream, defined by the wireless data packets. Additionally, the match may depend on a source and/or a destination of the wireless data packets. It is for example known to be able to determine if a packet stream is related to web browsing, e-mailing, computer gaming, media-streaming, VoWIFI/VoIP, etc. based on the size and pattern of a packet stream. For example, a stream of small packets every 15-25 milliseconds in both directions can with high probability be recognized as VoWIFI/VoIP.

Therefore, in accordance with an exemplary embodiment of the present invention the step of determining, in the router, if a stream of wireless data packets from the at least one client on board the public transport vehicle corresponds to at least one of a VoIP stream and a VoWIFI stream comprises:

determining at least one of a source, a destination, a size and pattern of the stream of wireless data packets, and using this for identification if the stream of wireless data packets corresponds at least one of a VoIP stream and a VoWIFI stream. In addition to, or as an alternative, the step of determining if a stream of wireless data packets from the at least one client on board the public transport vehicle corresponds to at least one of a VoIP stream and a VoWIFI stream comprises identification of a data packet type or data stream type for the stream of wireless data packets based on deep packet inspection.

The concept of analyzing packet size and shape of various packet streams in order to identify and determine the data stream type, as such, is per se known, and often utilized in traffic shaping or packet shaping. Traffic shaping techniques can be found in e.g. US2005/0172008, EP1912385, U.S. Pat. No. 7,061,860, US2004/0111461, Adaptiband™ by XRoads Networks, Radware's Deep Flow Inspection™, and NAVL by Procera Networks, all of which are hereby incorporated by reference. However, as far as is presently known, this has never been used on public transport vehicles, and in particular not for the same purposes as in the present invention. It has now been realized by the present inventors that these various ways of determining a type of data stream can be used to improve the travelling experience and increase passenger satisfaction on public transport vehicles, and in particular to enforce rules regarding silence and quietness in certain areas of the vehicle.

In accordance with another exemplary embodiment of the present invention the step of determining, in the router, if a stream of wireless data packets from the at least one client on board the public transport vehicle corresponds to at least one of a VoIP stream and a VoWIFI stream comprises:

comparing a destination address of the stream of wireless data packets to a blacklist comprising at least one predefined address. This is provides for an alternative or additional means for determining if a stream of wireless data packets corresponds to a at least one of a VoIP stream and a VoWIFI stream as compared to analyzing size and/or shape of the stream. A blacklist is in the present context to be interpreted as a defined list of IP-addresses and/or ports, where data streams associated with these IP-addresses/ports are intercepted and/or blocked when the client associated with the stream is within the access are of an access point set in a silent compartment mode. Preferably the blacklist comprises at least one IP-address associated with VoWIFI and/or VoIP protocols, e.g. a destination address. The blacklist may also be dynamically and periodically updated. Alternatively, or in addition to IP-addresses and/or ports, the blacklist may comprise a list of web addresses, enabling interception/blocking of streams when an attempt is made to contact certain web addresses via a DNS server. In such a case, the response from the DNS server may be communicated back to the user, but any subsequent attempts to reach this web address may be intercepted.

In a similar way as discussed above, it is also possible to detect e.g. attempts to set-up Skype-calls and the like, e.g. over the cellular network (3G/4G), and to prohibit hand over of the voice communication session to the router in order to handoff the voice communication session to a VoWIFI session. This further ensures that the rules of silence and quietness are followed.

The access point may be set in a silent compartment mode by means of hardware configuration on the access point or the router, such as by providing switch(es) or the like.

Alternatively or additionally, the access point may be set in a silent compartment mode by means of software configuration in the router. This may be done locally, by directly interacting with the router via an interface, such as a touch screen, a keyboard or the like. However, the software configuration for setting access point a silent compartment mode or in a normal compartment mode in said router may also be controllable from an external server, e.g. by means of cloud management. Thus, the setting of modes for the access points can be ordered from a central location, be enabled via a web interface, or the like.

-   For safety reasons, it may be desirable not to intercept certain     VoIP and VoWIFI calls. In particular, it may be desirable to enable     emergency calls at any time and at any location within the public     transport vehicle. -   Thus, in one embodiment, the method further comprises the step of     determining whether the VoIP stream or VoWIFI stream corresponds to     an emergency call, and if so, overriding said interception and allow     said stream regardless of whether the client is within the access     area of an access point set in a silent compartment mode or not. The     step of determining if a VoIP stream or a VoWIFI stream corresponds     to an emergency call may comprise comparing of a telephone phone     number to which said stream is directed to a whitelist comprising at     least one predefined emergency telephone number. The whitelist may     e,g, include telephone numbers such as 911 (used as an emergency     phone number in e.g. the US), 112 (used as an emergency phone number     in most of Europe), 999 (used as an emergency phone number in e.g.     the UK), etc.

According to another aspect of the present invention there is provided a wireless communication system for a public transport vehicle, such as a train, comprising:

at least one router in the public transport vehicle, said router being configured to receive and transmit wireless data packets to and from a stationary communication server outside said public transport vehicle through at least one exterior mobile network via at least one antenna, and to and from at least one client onboard the public transport vehicle via at least one access point connected to said router, wherein said access points are controllable to be set in a silent compartment mode, wherein said at least one router includes:

a controller configured to determine if a stream of wireless data packets from said at least one client on board the public transport vehicle corresponds to at least one of a VoIP stream and a VoWIFI stream; and to intercept said stream if it has been determined that said stream of wireless data packets corresponds to at least one of a VoIP stream and a VoWIFI stream and that said client associated with said stream is within the access are of an access point set in a silent compartment mode.

With this aspect of the invention, similar advantages and preferred features are present as in the previously discussed first aspect of the invention.

These and other features and advantages of the present invention will in the following be further clarified with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

For exemplifying purposes, the invention will be described in closer detail in the following with reference to embodiments thereof illustrated in the attached drawings, wherein:

FIG. 1 is a schematic illustration of a train having a wireless communication system in accordance with an embodiment of the present invention; and

FIG. 2 is a schematic flow chart illustrating a traffic forwarding sequence in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

In the following detailed description, some embodiments of the present invention will be described. However, it is to be understood that features of the different embodiments are exchangeable between the embodiments and may be combined in different ways, unless anything else is specifically indicated. It may also be noted that, for the sake of clarity, the dimensions of certain components illustrated in the drawings may differ from the corresponding dimensions in real-life implementations of the invention. Even though in the following description, numerous specific details are set forth to provide a more thorough understanding of e present invention, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well known constructions or functions are not described in detail, so as not to obscure the present invention.

In FIG. 1 a schematic illustration of a vehicle 1, such as a train, having a communication system, is provided. The communication system comprises a data communication router 2 for receiving and transmitting data between an internal local area network (LAN) 3, and one or several external wide area networks (WANs) 4 a, 4 b, 4 c. Specifically, the router 2 preferably includes a captive portal (sometimes referred to as a captive portal policy) which allows an administrator to block internet access for users until they complete an authentication process. Conventionally captive portals are known to be utilized e,g, by public WiFi-hotspots. Communication to and from the WANs is provided through two or more antennas 5 a-n on the vehicle roof. Two or more data links are preferably available, either between the train and one of the WANs, and/or by using several WANs simultaneously.

The LAN is preferably a wireless network, using one or several internal antennas—in the following referred to as access points—to communicate with clients 6 within the vehicle 1. The LAN may be set-up as WiFi wireless access point(s). The client(s) 6 may be computing devices such as laptops, mobiles telephones, PDAs and so on.

The data communication router comprises a plurality of modems 21 a-n. Assignment of data streams to different WANs and/or to different data links on one WAN is controlled by a control unit 23 (also known as a controller 23). The control unit 23 is preferably realized as a software controlled processor. However, the controller 23 may alternatively be realized wholly or partly in hardware.

The control unit 23 is furthermore preferably arranged or configured to determine if wireless data packets match or correspond to at least one of a VoIP stream and a VoWIFI stream. Moreover, the control unit 23 is preferably configured to forward the stream of wireless data packets if it is determined that the stream corresponds to at least one of a VoIP stream and a VoWIFI stream, regardless of whether the client associated with that particular stream of wireless data packets is authenticated by the authentication process (provided by the captive portal) or not. This allows the router to effectively bypass the captive portal when detecting a VoIP call or a VoWIFI call, for the convenience of the passengers.

The system may also comprise a GNSS (Global Navigation Satellite System) receiver, such as a global positioning system (GPS) receiver 7, for receiving GNSS/GPS signals indicative of the current position of the vehicle, and wherein the controller may be arranged to use this data e.g. to comply with national regulations etc.

The data communication router may also be denominated MAR (Mobile Access Router) or MAAR (Mobile Access and Applications Router).

The determining and the associated analysis (packet sniffing) of the received data packets may be realized in various ways. For example, it may involve comparing a destination address of a stream of data packets to a blacklist comprising at least one defined address. The blacklist is configurable by a user or administrator of the network, and a plurality of carriers use the same destination address(es) for their VoIP/VoWIFI services, thus they can be anticipated and accordingly entered into the blacklist.

The data communication router is preferably arranged to communicate on at least two different communication routes having different characteristics. Hereby, the communication can be automatically optimized based on specific conditions, such as price, speed, etc. Such data communication routers are known from EP 1 175 757 and EP 2 943 011 by the same applicant, said documents hereby incorporated by reference. Such routers are also commercially available from the applicant, Icomera AB. Hereby, the router may use all available data channels, such as two or more of e.g. Satellite, HSPA, EDGE, EVDO, LTE, LTE-A, WiFi (802.11) and WiMAX; and combine them into one virtual network connection. An automatic selection is then made among the available channels to use the most cost efficient combination that fulfills the users' availability, bandwidth and reliability requirements. Hence, a seamless distribution of the data among said different channels is obtained.

The transferring of data streams through different data links may additionally or alternatively comprises the two main steps: evaluation and assignment. Each of these permits some variability. Numerous types of tests, generating a predictable response, such as an echo, could be performed to evaluate link quality, and such tests can be combined in any order, serially or in parallel. The following are only examples.

Any of a variety of common Internet functions can be taken to indicate the usefulness of a link. For example, a WWAN Internet service provider (ISP) will normally offer the addresses of one or more domain name system (DNS) servers, an essential service. DNS queries can be bound to each link, to attempt to resolve a largely arbitrary domain name using one of the ISP's provided servers, or any other. Failure to respond within a given time frame is taken to mean either a general problem transferring the small amount of data, or a more specific problem with the queried DNS server.

If the queried DNS server belongs to the ISP, the latter will often indicate a severe problem at the ISP for that specific link. Because a DNS request typically consists of a single UDP or TCP packet going each way, this type of test is very light. The infrastructure typically prioritize DNS queries and DNS responses highly in traffic control algorithms, which is another reason why this type of test can be expected to complete very quickly, if at all. The timeout on it can therefore be set very low, producing high responsiveness. The lightness of a DNS test is both an advantage and, to some extent, a drawback. It detects qualitative problems, and is very quick. It also results in a low transfer of data, and does not strain the link, which in turn means that the tests can be repeated very frequently. However, because it does not strain the link, it is a poor indicator of quantitative performance.

Another example of an embodiment therefore uses the ICMP protocol. In this protocol, an ECHO_REQUEST datagram is used to elicit an ECHO_RESPONSE from an arbitrary remote host, preferably a very stable one.

In normal use, ICMP testing is light in the same way as DNS testing. In addition, it is easier for ISPs to prioritize ICMP in unknown ways, because it is a special protocol and does not represent an essential service. Unpadded ICMP requests are likely to receive a very high priority, because ICMP is a standard test of network latency. When highly prioritized, it gives the illusion of good overall responsiveness, while payload data in other types of containers gets a lower priority and relatively poor performance in case of congestion.

As part of the protocol, ICMP packets can be padded with extra bytes of data. This provides a simple, universally recognized method of loading down a link with a very precise burst of traffic, and timing the response. The fact that one and the same packet constitutes the load and is timed is the greatest virtue of this test, because it measures how heavy traffic on a link will actually be treated. In practice, there is often a substantial difference in how a stream of ICMP packets is treated, depending on their size. When padded packets fail to arrive under a given timeout, this is an indicator of performance problems.

The ICMP request may be sent to any type of stationary communication server accessible through the exterior network, such as a DNS server, a gateway through which the communication from the moving vehicle is transferred, a content provider server, or the like.

These embodiments for evaluation mentioned thus far can be generalized as one: any active sending of a request or other provocation across a network, through a specific link, with the expectation of receiving a response under a timeout or corresponding safeguard. Variations on this theme include factors such as protocol, target host location, the amount of traffic sent and solicited, and the precise limit set by the timeout function. Obviously, factors external to the individual test, such as the interval between repetitions of the same type of test, is also a potential subject of fine tuning.

In FIG. 2 a schematic flow chart of a method for wireless communication between a public transport vehicle and a remote server through at least one external mobile network 4, according to an embodiment of the invention, is illustrated. The figure shows the traffic forwarding sequence in a schematically represented router 2. Data packets are sent and received, as indicated by the arrows 11, between a set of clients 6, here illustrated as smart phones, and an external mobile network 4, via the router 2. The data packets are received 201 by the router 2, or any other suitable network edge device. In a subsequent process step 202, the type of data packets are determined. The determining step 202 starts with an analysis of the data packets, where it is to be determined if the stream of data packets correspond to a stream of VoIP data packets or a stream of VoWIFI data packets. The analysis can be done by checking the size and pattern of the data packet stream as defined by the received packets. The analysis can also be performed by additionally or alternatively checking source and/or destination of the packets. For example, the determining step 202 may include a comparing step, where a destination address of the stream of data packets is compared to a blacklist 210 comprising at least one predefined address. However, the analysis of the data packets may be performed in various ways, as earlier stated, according to specific requirements or needs.

If it is determined that the stream of data packets do not correspond to a stream of VoIP data packets or a stream of VoWIFI data packets, then the stream is forwarded in a normal way, in subsequent step 204.

However, if it is determined that the stream of data packets does correspond to VoIP or VoWIFI, it is determined in a next step 203 whether the client associated with the stream is within the access area of an access point set in a silent compartment mode. This is in order to check if the client 6, that is associated with the stream of data packets attempts to make or receive a telephone call despite the fact that it is at present located in a silent coach/compartment of the vehicle.

If it is determined in step 203 that the client is not in a silent compartment/coach, the stream is forwarded in a normal way, step 204.

However, if it is determined that the access point presently handling the client is in a silent compartment mode, the stream will be intercepted, step 211.

The present invention has here mainly been disclosed in relation to trains, where it is considered to be particularly advantageous. However, it may also be implemented and used on other public transport vehicles, and in particular vehicles intended for passenger traffic, such as buses, ferries, airplanes, etc. 

1. A method for wireless communication between a public transport vehicle and a remote server through at least one external mobile network, comprising: providing at least one router in the public transport vehicle for receiving and transmitting wireless data to and from a stationary communication server outside said public transport vehicle through said at least one external mobile network via at least one antenna and being connected to at least one access point for receiving and transmitting wireless data to and from at least one client onboard the public transport vehicle; determining if a stream of wireless data packets received by said router corresponds to at least one of a VoIP stream and a VoWIFI stream; determining if the client associated with said stream is within the access area of an access point which is set in a silent compartment mode; and intercepting said stream if it has been determined that said stream of wireless data packets corresponds to at least one of a VoIP stream and a VoWIFI stream and that said client associated with said stream is within the access are of an access point set in a silent compartment mode.
 2. The method according to claim 1, wherein the step of determining if a stream of wireless data packets from said at least one client on board the public transport vehicle corresponds to at least one of a VoIP stream and a VoWIFI stream comprises: determining at least one of a source, a destination, a size and pattern of the stream of wireless data packets, and using this for identification if said stream of wireless data packets corresponds to at least one of a VoIP stream and a VoWIFI stream.
 3. The method according to claim 1, wherein the step of determining if a stream of wireless data packets from said at least one client on board the public transport vehicle corresponds to at least one of a VoIP stream and a VoWIFI stream comprises identification of a data packet type or data stream type for said stream of wireless data packets based on deep packet inspection.
 4. The method according to claim 1, wherein the step of determining if a stream of wireless data packets from said at least one client on board the public transport vehicle corresponds to at least one of a VoIP stream and a VoWIFI stream comprises: comparing a destination address of said stream of wireless data packets to a blacklist comprising at least one predefined address.
 5. The method according to claim 1, wherein the step of determining if a stream of wireless data packets from said at least one client on board the public transport vehicle corresponds to at least one of a VoIP stream and a VoWIFI stream comprises: comparing a output port of said stream of wireless data packets to a blacklist comprising at least one predefined output port.
 6. The method according to claim 1, wherein access point are set in a silent compartment mode by means of hardware configuration on the access point or the router.
 7. The method according to claim 1, wherein access point are set in a silent compartment mode by means of software configuration in the router.
 8. The method according to claim 7, wherein the software configuration for setting access point a silent compartment mode or in a normal compartment mode in said router is controllable from an external server.
 9. The method according to claim 1, further comprising the step of determining whether the VoIP stream or VoWIFI stream corresponds to an emergency call, and if so, overriding said interception and allow said stream regardless of whether the client is within the access area of an access point set in a silent compartment mode or not.
 10. The method of claim 9, wherein the step of determining if a VoIP stream and/or a VoWIFI stream corresponds to an emergency call comprises: comparing a telephone phone number to which said stream is directed to a whitelist comprising at least one predefined emergency telephone number.
 11. A wireless communication system for a public transport vehicle comprising: at least one router in the public transport vehicle, said router being configured to receive and transmit wireless data packets to and from a stationary communication server outside said public transport vehicle through at least one exterior mobile network via at least one antenna, and to and from at least one client onboard the public transport vehicle via at least one access point connected to said router, wherein said access points are controllable to be set in a silent compartment mode, wherein said at least one router includes: a controller configured to determine if a stream of wireless data packets from said at least one client on board the public transport vehicle corresponds to at least one of a VoIP stream and a VoWIFI stream; and to intercept said stream if it has been determined that said stream of wireless data packets corresponds to at least one of a VoIP stream and a VoWIFI stream and that said client associated with said stream is within the access are of an access point set in a silent compartment mode.
 12. The wireless communication system according to claim 11, wherein the access points are controllable to set in a silent compartment mode by means of hardware configuration on the access point or the router.
 13. The wireless communication system according to claim 11, wherein the access point are controllable to be set in a silent compartment mode by means of software configuration in the router.
 14. The wireless communication system according to claim 13, wherein the software configuration for setting access point a silent compartment mode or in a normal compartment mode in said router is controllable from an external server. 